Controlled tissue compression systems and methods

ABSTRACT

A surgical instrument is provided including an end effector configured to clamp, staple or cut tissue tissue, a motor configured to drive the end effector and a control system. The control system is configured to receive information about at least one tissue property and select a tissue management mode based on the at least one tissue property. The control system controls the motor based on the selected tissue management mode.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of and priority to U.S.Provisional Application Ser. No. 61/445,700, filed on Feb. 23, 2011, theentire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to medical devices. Morespecifically, the present disclosure relates generally to systems andmethods for controlled tissue compression.

2. Background of the Related Art

Some surgical procedures require the compression, e.g., clamping, of apatient's tissue. Such procedures may include, e.g., anastomosing,stapling, and resecting of tissue. For example, where cancerous tissueis identified in a patient's gastrointestinal tract, the canceroustissue may need to be surgically removed. Where, for example, thecancerous tissue is located on the colon and is accessible by surgicalinstrumentation, the surgeon may make an incision in the patient'sabdomen to allow access to the bowel. The surgeon may then use a linearcutting and stapling device, such as that described in U.S. patentapplication Ser. No. 12/235,362, filed Sep. 22, 2008 (U.S. PatentPublication No. 2009/0101692), which is expressly incorporated herein inits entirety by reference thereto, to cut and staple the colon tissue onopposite sides of the cancerous portion to be removed. In thisprocedure, the colon is externally clamped (e.g., between opposed jaws)to compress the tissue. While the tissue is compressed, a cutter and astapler are activated to make a linear cut and apply typically twolinear rows of staples in the areas adjacent the cut. The stapling thuscloses both open ends of the portion of the bowel to be removed, as wellas providing a temporary closure of the two cut ends of the bowel. Thisclosure limits exposure of the surrounding tissue to the interior of thebowel, thus limiting the risk of infection. After the cutting andstapling procedure, the cancerous portion of tissue may be removed fromthe patient's body.

After the resection of the cancerous tissue, the surgeon may employ ananastomosing and stapling device, e.g., a circular stapler/cutter, suchas that described in U.S. patent application Ser. No. 10/785,682, filedFeb. 24, 2004 (U.S. Pat. No. 7,342,983), which is expressly incorporatedherein in its entirety by reference thereto. During this procedure ahead portion is positioned within the colon adjacent one of the cut endsand a base or shaft portion is positioned within the colon adjacent theother cut end. The head portion and the base portion may be coupled viaa shaft and/or cable that extends out of one cut end and into the other.Via this coupling, the surgeon is able to actuate the anastomosing andstapling device to draw the head portion and the base portion together.After the two cut ends of the colon contact each other, the actuationcontinues such that the two portions of the colon are clamped togetherat an annular area of contact. While clamped, the anastomosing andstapling device may be further actuated to apply an annular ring ofstaples into the compressed tissue. The device may also cut excesstissue disposed within the colon. The head portion and the base portionare then moved apart and the anastomosing and stapling device removedfrom the patient.

To achieve effective stapling in the above procedures, the tissue mustbe compressed to the extent that there is an adequately small tissuegap, e.g., one millimeter, between the faces of the tool. If theclamping structures of the instrument are exposed to excessive force,maintaining a uniform target tissue gap across the length of tissue tobe stapled may be difficult or even impossible.

Moreover, when performing the compression, a constant closing rate(e.g., the closing rate between jaws of a linear stapler or between thehead and base portion of a circular stapler/cutter) may exert a highlevel of pressure on the clamped tissue. This high level of pressure mayresult in excess tissue trauma. It is thus desirable to limit thistrauma, e.g., by effectively controlling the pressure applied to thetissue.

Further, it is desirable to determine how the tissue to be clamped isresponding to compression and process this information to determineclamping pressure. U.S. patent application Ser. No. 09/510,927, filedFeb. 22, 2000 (now U.S. Pat. No. 6,716,233), which is expresslyincorporated herein in its entirety by reference hereto, describesapparatus and methods of using a tissue sensor to control operation of asurgical stapler.

SUMMARY

In an embodiment of the present disclosure, a surgical device isprovided. The surgical device includes an end effector configured toclamp, staple or cut tissue, a motor configured to drive the endeffector and a control system. The control system receives informationabout at least one tissue property and selects a tissue management modebased on the at least one tissue property. The control system controlsthe motor based on the selected tissue management mode.

The surgical device may also include an indicator that provides aclinician with a status of a tissue gap range of the end effector and asensor array configured to detect at least one tissue property. Thesensor array may detect at least one tissue property by measuring thecurrent draw on the motor or the dwell effect at the end effector. Thesensor array may also assess tissue properties by taking measurementssuch as pulse oximetry, tissue oxygen saturation or tissue impedance.The dwell effect occurs as the jaws remain at a static pressure for aperiod and fluids escape from the tissue cells, allowing the tissue torelax.

The tissue management modes that can be selected by the surgical deviceinclude a constant torque profile, a modulated torque profile, a maximumtorque profile or a manual override mode. The control system applies aconstant signal to the motor in the constant torque profile or aperiodic signal to the motor in the modulated torque profile. In themaximum torque profile, the powered surgical instrument fires at a speedthat is faster than the speed of firing in the constant torque profile,the modulated torque profile or the manual override mode. In the manualoverride mode, the user manually controls the motor. Typically, pressureduring tissue clamping will be a function of the motor torque.

In another embodiment of the present disclosure, a method for applying astaple by a powered surgical instrument is provided. The method includesthe steps of providing a surgical instrument having an end effector thatis powered by a motor, inputting a tissue type and/or disease type todetermine an initial clamping or tissue management mode, clamping tissueusing the end effector driven by the motor, detecting at least onetissue property of the clamped tissue, determining if a desired tissuegap range is achieved by the end effecter, if necessary, selecting anadditional clamp mode to iteratively adjust clamping to achieve thedesired tissue gap, and firing the powered surgical instrument to applystaples to the clamped tissue once the desired tissue gap has beenachieved.

The method may also include the step of providing an indication of astatus of a tissue gap range. The tissue property may be detected bymeasuring the current draw on the motor or measuring a dwell effect atthe end effector.

Selecting the clamping or tissue management mode may be based on thetissue property of the clamped tissue detected or be performed by aclinician. The tissue management modes that can be selected by thesurgical device include a constant torque profile, modulated torqueprofile or maximum torque profile. A manual override mode may allow theuser to select a tissue management mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective view of a powered surgical instrument accordingto an embodiment of the present disclosure;

FIG. 2 is a system block diagram of the powered surgical instrumentaccording to an embodiment of the present disclosure;

FIG. 3 is a flow chart depicting operation of the powered surgicalinstrument according to an embodiment of the present disclosure; and

FIG. 4 is a flow chart depicting an indicator system according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, it isto be understood that the disclosed embodiments are merely exemplary ofthe disclosure and may be embodied in various forms. Well-knownfunctions or constructions are not described in detail to avoidobscuring the present disclosure in unnecessary detail. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to variouslyemploy the present disclosure in virtually any appropriately detailedstructure.

Like reference numerals may refer to similar or identical elementsthroughout the description of the figures. As shown in the drawings anddescribed throughout the following description, as is traditional whenreferring to relative positioning on a surgical instrument, the term“proximal” refers to the end of the apparatus which is closer to theuser and the term “distal” refers to the end of the apparatus which isfarther away from the user. The term “clinician” refers to any medicalprofessional (i.e., doctor, surgeon, nurse, or the like) performing amedical procedure involving the use of embodiments described herein.

A powered surgical instrument, e.g., a surgical stapler, in accordancewith the present disclosure is referred to in the figures as referencenumeral 100. Powered surgical instrument 100 is merely an example of asurgical instrument that utilizes the embodiments of the presentdisclosure described herein and therefore, is not intended to limit thepresent disclosure to this one particular embodiment of a surgicalinstrument.

Referring initially to FIG. 1, powered surgical instrument 100 includesa housing or handle 110, an endoscopic portion 140 defining alongitudinal axis A-A extending therethrough, and an end effector 160,defining a longitudinal axis B-B (illustrated substantially aligned withaxis A-A in FIG. 1) extending therethrough. Endoscopic portion 140extends distally from housing 110, and clamping mechanism or endeffector 160 is disposed adjacent a distal portion 142 of endoscopicportion 140. End effector 160 is used to clamp, staple and/or cut tissuedisposed therebetween.

Powered surgical instrument 100 may include a control system designatedgenerally as 200 in FIG. 2. Control system 200 may be integrated inhousing 110 of powered surgical instrument 100 or some of the componentsmay be provide in a stand-alone unit. Control system 200 includes aprocessor 202, an input device 204, a display 206, a memory 208, anindicator 210, a motor 212 and a sensor array 214.

Processor 202 may be an integrated circuit or may include analog and/orlogic circuitry that may be used to: execute instructions according toinputs provided by the input device 204 or sensor array 214; executeinstructions according to a program provided in memory 208; and/orcontrol motor 212 thereby controlling the end effector 160 to clamp,staple and/or cut tissue therebetween.

Input device 204 may include a keyboard, a touchscreen input device,switches and/or buttons to control operation of the powered surgicalinstrument 100. Input device 204 may be used to: select between tissuemanagement modes; control end effector 160; apply a staple or clamp; andinput tissue properties such as tissue type and/or disease.

Display 206 may include a liquid crystal display, a light emitting diodedisplay or the like. Display 206 may output a status of the poweredsurgical instrument, the measured tissue properties, the number ofstaples/clips applied, etc.

Control system 200 may also include an indicator 210 that may include atleast one light emitting diode (LED) to indicate whether a tissue gaprange, between the jaws of end effector 160, has been met. Indicator 210may include a single multi-color LED or separate LEDs for red, yellowand green. The red LED may indicate a malfunction, a yellow LED mayindicate that a tissue gap range has not been met and a green LED mayindicate that the tissue gap range has been met. Additionally, an LEDmay be pulsed to indicate additional information. For instance, apulsing yellow LED can indicate that an additional clamping cycle isbeing performed.

Sensor array 214 determines tissue properties by detecting the currentdraw on motor 212 or a dwell effect at end effector 160. The detectedtissue properties are used to determine a clamping or tissue managementmode, a tissue gap range, firing parameters, a speed of the motor, amodulation/pulse of the motor, deployment of the staples, etc. Thetissue properties are used as an input to the iterative adjustment ofthe clamping pressure and duration for a tissue management mode.

Memory 208 may be a volatile type memory (e.g., RAM) and/or non-volatiletype memory (e.g., flash media, disk media, etc.) that stores programsor sets of instructions for the operation of the powered surgicalinstrument 100.

Such programs include a number of tissue management modes that may beused to clamp tissue in order to apply a staple or clip to the tissuegrasped by end effector 160. The tissue management modes are selected toapply an atraumatic stress or strain to the tissue by varying thecompression of the tissue. The tissue management modes include aconstant torque profile, a modulated torque profile, a maximum torqueprofile and a manual override mode. The tissue management modes may beautomatically selected based on detected tissue parameters and/or tissuetype and disease type inputted by a clinician or the tissue managementmode may be selected by a clinician.

When a constant torque profile is selected, the powered surgicalinstrument 100 uses controlled tissue compression to apply constant rateif strain to tissue during the clamp, dwell and firing stages tooptimize tissue gap and staple formation by applying a constant signalto motor 212 from processor 202. The parameters used to control themotor 212 and/or end effector 160 in the constant torque profile may bebased on a desired speed of firing of the surgical instrument 100 or thetype of tissue grasped by end effector 160.

The modulated torque profile applies pulsating or periodic strain energyto tissue by applying a periodic signal to motor 212. More specifically,processor 202 applies a pulse width modulated signal (PWM) or any otherperiodic signal to the motor to achieve an optimized compressionprofile, i.e., minimum tissue gap (maximum strain) with minimum tissuetrauma (minimum stress). The optimized compression profile may vary fordifferent tissue types and/or disease types. The signal from processor202 may be predetermined and stored in a memory. Alternatively, thesignal outputted by processor 202 may be determined by performing acurrent slope analysis on the current detected from the motor, initialtissue thickness T₀, initial clamped tissue thickness T₁ and totalstrain/energy.

When the tissue management mode is set for operation in the maximumtorque profile, the surgical instrument 100 fires relatively faster thanthe other modes of operation. While in the maximum torque profile,surgical instrument 100 fires relatively faster at the beginning and atthe end of the stroke where device stresses are relatively lower. Whenthe tissue management mode is set to operate in the manual overridemode, the clinician can manually control the motor of surgicalinstrument 100 to achieve the desired tissue gap of end effector 100 andto manually fire the surgical instrument 100.

Memory 208 may also store correlation tables to correlate tissue typeand disease type to the requisite tissue gap range and firing parametersthat need to be achieved to successfully apply a staple or clip totissue.

FIG. 3 depicts a flow chart describing an operation of the controlsystem 200 of powered surgical instrument 100. As shown in FIG. 3, aclinician starts, “powers-up” or “turns on” the powered surgicalinstrument 100 in step 300. A clinician enters the tissue type and/ordisease type in step 305 using input device 204. The clinician thenpositions end effector 160 onto the desired tissue and an initialclamping (tissue management) mode is determined. Then, in step 315, endeffector 160 clamps the desired tissue and determines tissue propertiessuch as initial thickness, density, initial clamped thickness, etc. instep 320. Processor 202, then, in step 325, determines if the tissue gaprange is met for the particular tissue type. If the gap range is met,the control system 200 proceeds to step 370.

In step 325, if the gap range is not met, the tissue gap and tissueproperties are evaluated by processor 202 to determine if additionalclamping is beneficial. If it is, the gap range and tissue propertiesare used to determine a new clamping mode in step 327. The iterativeclamping and evaluation process then returns to step 315 and iscontinued until an optimum gap range is met or it is determined that thetissue is unsuitable for the selected range in which instance thepowered surgical instrument 100 prompts the clinician with a suggestionif a different reload or end effector (loaded with a different sizedstaple) should be used. If the clinician selects a different reload orend effector, then the powered surgical instrument 100 is reloaded instep 340 and proceeds to step 315 to clamp tissue.

If the clinician does not select a different reload or end effector, theclinician may select a manual override mode in step 345. If the userselects the manual override mode, the powered surgical instrument 100 isplaced in the manual override mode in step 350.

Alternatively, the process proceeds to step 355 to select a tissuemanagement mode. The tissue management mode may be automaticallyselected by processor 202 based on the inputted tissue type, diseasetype, and/or tissue properties or selected by the clinician. Based onthe selection of the tissue management mode, the powered surgicalinstrument 100 may enter the constant torque profile of step 362,modulated torque profile of step 364 or the maximum torque profile ofstep 366. Then the control system 200 proceeds to step 370 where adetermination is made as to whether a staple should be applied. Thisdetermination may be made by processor 202 or by the clinician. If thestaple should be applied, then in step 375, the control system 200controls the powered surgical instrument 100 to apply the staple. If thestaple is not applied, the control system 200 ends the procedure (step380) or restarts to apply a subsequent staple (step 300).

FIG. 4 depicts a flow chart describing an operation of the indicatorsystem of the powered surgical instrument 100. The powered surgicalinstrument 100 is started in step 400 and the tissue type and/or diseaseis entered in step 405. Processor 202 then uses one of the correlatingtables stored in memory 208 to determine the tissue gap range for thered-yellow-green indicator 210. The tissue gap range is measured in step415. If an error is determined or the tissue gap range exceeds an upperlimit, the process proceeds to step 430 and the red indictor isilluminated. If there is no error or the tissue gap range does notexceed an upper limit, the process proceeds to step 435. If the tissuegap range is not in the acceptable range but it does not exceed theupper limit, the yellow indicator is illuminated in step 440. If thetissue gap range is met, the process proceeds to step 445 and the greenindicator is illuminated.

It should be understood that the foregoing description is onlyillustrative of the present disclosure. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the disclosure. Accordingly, the present disclosure isintended to embrace all such alternatives, modifications and variances.The embodiments described with reference to the attached drawing figs.are presented only to demonstrate certain examples of the disclosure.Other elements, steps, methods and techniques that are insubstantiallydifferent from those described above and/or in the appended claims arealso intended to be within the scope of the disclosure.

1. A surgical device comprising: an end effector configured to clamp,staple or cut tissue; a motor configured to drive the end effector; anda control system configured to: receive information about at least onetissue property; select a tissue management mode based on the at leastone tissue property; and control the motor based on the selected tissuemanagement mode.
 2. The surgical device according to claim 1, whereinthe control system further comprises an indicator that provides aclinician with a status of a tissue gap range of the end effector. 3.The surgical device according to claim 1, wherein the control systemfurther includes a sensor array configured to detect at least one tissueproperty.
 4. The surgical device according to claim 3, wherein thesensor array detects a tissue property by measuring a current draw onthe motor.
 5. The surgical device according to claim 3, wherein thesensor array detects a tissue property by measuring a dwell effect atthe end effector.
 6. The surgical device according to claim 1, whereinthe tissue management mode is a constant torque profile, a modulatedtorque profile, a maximum torque profile or a manual override mode. 7.The surgical device according to claim 6, wherein the control systemapplies a constant signal to the motor in the constant torque profile.8. The surgical device according to claim 6, wherein the control systemapplies a periodic signal to the motor in the modulated torque profile.9. The surgical device according to claim 6, wherein the poweredsurgical instrument fires at a speed that is faster than the speed offiring in the constant torque profile, the modulated torque profile orthe manual override mode when the powered surgical instrument uses themaximum torque profile.
 10. The surgical device according to claim 6,wherein a user manually controls the motor in the manual override mode.11. A method of applying staples by a powered surgical instrument, themethod comprising the steps of: providing a surgical instrument havingan end effector that is powered by a motor; inputting tissue type and/ordisease type; clamping tissue using the end effector driven by themotor; detecting at least one tissue property of the clamped tissue;determining if a desired tissue gap range is achieved by the endeffector; selecting a tissue management mode to clamp tissue to achievethe desired tissue gap; and firing the powered surgical instrument inthe selected tissue management mode to apply staples to the clampedtissue.
 12. The method according to claim 11 further comprising the stepof providing an indication of a status of a tissue gap range.
 13. Themethod according to claim 11, wherein the step of detecting at least onetissue property further includes measuring a current draw on the motor.14. The method according to claim 11, wherein the step of detecting atleast one tissue property further includes measuring a dwell effect atthe end effector.
 15. The method according to claim 11, wherein the stepof selecting the tissue management mode is based on the at least onetissue property of the clamped tissue detected.
 16. The method accordingto claim 11, wherein the step of selecting the tissue management mode isperformed by a clinician.
 17. The method according to claim 11, whereinthe tissue management mode is a constant torque profile, modulatedtorque profile, maximum torque profile or a manual override mode. 18.The method according to claim 11, further comprising the step of thepowered surgical instrument suggesting a different reload when thedesired tissue gap range for the end effector is not achieved.